With the advent of the soil resistant yarn finish disclosed in U.S. Pat. No. 4,192,754, hereby incorporated by reference, it was desirable to modify the yarn polymer properties to enhance the retention by yarn of the fluorocarbon component in the yarn finish. It was discovered that yarn of deep dyeable polymer which has a high number of amine ends, also has improved permanency of the soil resistant fluorocarbon finish on the yarn. However, the amine additives, used to provide the prior art deep dyeable yarn polymers, such as cyclohexylamine or hexamethylenediamine were not entirely satisfactory. Cyclohexylamine, which is conventionally used in continuous melt polymerization processes to control dyeability and degree of polymerization, for example, did not provide enough amine ends for improved retention of the fluorocarbon component of the yarn finish; and hexamethylenediamine caused runaway polymerization rates, i.e., a polymer melt that was not stable during continuous polymerization and/or spinning of fiber.